Question

已知a=，求的值．

Answer 1

【答案】分析：先化简，再代入求值即可．
解答：解：∵a=，
∴a=2-＜1，
∴原式=-
=a-1-
=a-1+
=2--1+2+
=4-1
=3．
点评：本题考查了二次根式的化简与求值，将二次根式的化简是解此题的关键．